Internal-combustion engine and carburetor-induction system therefor



y 1954 E, c. KIEKHAEFER 2,684,056

INTERNAL-COMBUSTION ENGINE AND CARBURETOR-INDUCTION SYSTEM THEREFOR Filed July 26, 1950 \1 mom k flew? z gg r, I y

I 22 I 22 27 /Z Patented July 20, 1954 UNITED STATES PATENT OFFICE INTERNAL-COMBUSTION ENGINE AND CAR- BURETOR-INDUCTION SYSTEM THERE- FOR 3 Claims. 1

This invention relates to two-cycle internalcombustion engines and particularly to carburetors for engines which are normally disposed with the crankshaft on a vertical axis.

The invention provides in certain engines a carburetor having air control valve and fuel supply means particularly disposed for the equal delivery of fuel to adjacent crank chambers or cylinders where the carburetor supplies both chambers or cylinders.

A principal object of the invention is to assure equal delivery of the fuel to both chambers at all speeds or positions of carburetor air valve adjustment. 7

Another object is to avoid the unequal distribution of fuel by reason of the tendency of the fuel in passing through the carburetor to be directed to one wall or one side of the carburetor passage.

A more particular object is to dispose the carburetor jets in relation to the shutter controlling the flow of air and the jets and shutter in relation to the manifold passages to the respective cylinders or chambers so that the fuel mixture is delivered substantially equally to both cylinders or chambers at all times.

These and other objects and advantages will be more fully set forth in the following description of a preferred embodiment of the invention illustrated. in the accompanying drawings.

In the drawings:

Figure 1 is a side elevation of a two-cylinder, two-cycle engine with parts thereof broken away and sectioned to show the separate, upper and lower crank chambers and the carburetor located adjacent the chambers for delivery of the fuel mixture thereto;

Fig. 2 is an enlarged cross section of the carburetor and part of the engine as taken on line 2-2 of Fig. l; and

Fig. 3 is an enlarged vertical section taken on line 33 of Fig. 2 including the fuel intake manifold portions of the engine.

The two-cylinder, two-cycle, alternate-firing engine I, shown in the drawings, includes the crankshaft 2 which is disposed vertically as in an outboard motor, not shown.

The crankcase member 3 and cylinder block '4 form the crankcase 5 journally supporting crankshaft 2 in the upper and lower bearings 6. The split bearing unit 1 is pre-assembled on the center bearing 8 of crankshaft 2 intermediate the upper and lower, opposite crank-throws 9 and it, respectively, and in the completed engine, unit '5 is disposed within crankcase 5 to divide the chambers II and I2, respectively.

latter into the separate upper and lower crank The upper and lower cylinder bores i3 and it open into corresponding chambers i l and i2, respectively, and as shown comprise sleeves cast in block 4 to carry the pistons 55. Pistons in are connected to the corresponding crank-throws 9 and H! by the connecting rods it and operate in alternate firing sequence.

Two passages H are formed in block t adjacent cylinder bores I3 and I l to communicate with the corresponding crank chambers i i and i2 and open through ports l8 into the respective cylinder bores. The ports [9 opening from bores H and I2 into suitable exhaust discharge means, not shown, provide for exhaust of the cylinders. Ports i8 and it are located with respect to the stroke of pistons 15 so that the ports of each cylinder are opened by the piston operating therein at the end of the downward stroke and are otherwise closed by the skirt 2% of the piston.

In the two-cycle operation of the engine, the fuel mixture is drawn into chambers H and H with each up-stroke of the respective piston 25 and compressed within the chamber in the succeeding downstroke until the piston uncovers ports l8 and 19.

Ports l9 are spaced to be opened slightly ahead of the opening of ports [8 to allow blow-down of the cylinder exhaust gases so that upon opening of ports I8 the compressed fuel mixture in the corresponding crank chamber will pass or be transferred through passage ll into the cylinder to recharge the latter for the next succeeding stroke of the piston.

The carburetor 2| secured to member 3 provides the fuel mixture for admission to chambers H and [2 which is controlled and effected through passages 22 formed in the bearing unit I and opening upwardly into chamber H and downwardly into chamber it. The reeds 23 are normally disposed fiat against the upper and lower faces of unit 7 and over-lying the passage openings. Each reed 23 is secured at one end to unit I and the free end is adapted to be flexed against the fixed backing member 24 to open the passage 22. Reeds 23 on each side of unit i open and close passages 22 to the respective chambers H and I2 in response to pressure variations effected by pistons [5 in the operation of the engine, as described above, and prevent at any time the return or loss of fuel mixture from the chambers back into passages 22.

The mixture of liquid fuel and air for combustion is effected in the mixing chamber 25 of carburetor 2|. Chamber 25 is open at its outer end to receive the air from the atmosphere and in communication at its inner end through the registering opening 26 in crankcase member 3 with passages 22 of unit I.

The bearing unit 1 in providing an improved carburetion induction is simlar to that described and claimed in the copending application of the present-inventor, Serial No. 117,325 and filed September 23, 1949, for crankcase Induction Valve for Two-Cycle Engine, now Patent Number 2,612,882, issued October 7, 1952.

The butterfly valve shutter 21 mounted on the shaft 23 is rotatably disposed within chamber 25 to control the induction of air in the operation of engine I whereby the speed of the engine may be controlled.

In high speed position shutter 27 is disposed substantially parallel to the direction of flow of air through chamber 25. The tube 29 delivering th principalliquid fuel from the supply passage 38 to chamber 2-5 for mixing with the air or carburetion extends to the center of the chamber in a plane substantially 90 from the of shaft 28 of valve 2'! and is open at its end to face the Wall of chamber 25 opposite passage St.

The chamber SI in carburetor 2! is disposed adjacent chamber 25 and is provided with the two small holes 32. Holes 32 open into chamber 25 on opposite sides of shutter 21 when the shutter is in the full closed position so that air entering the outer hole mixing with the liquid fuel in chamber 3! passes through inner hole 32 and provides for the supply of liquid fuel under low speed or idling conditions as controlled by the shutter.

According to the invention the relative positions of shutter 2?, tube 2e and holes 32 with respect to engine I and particularly chambers H and I2 are determined by the relative positions of chambers H and I2 or in engine I by the vertical position of crankshaft 2.

Shutter 27, mounted on shaft 28, is turnable on a vertical axis so that in any intermediate position as shown in 2 the air is deflected sidewise by the shutter and not in a direction toward either chamber H or E2 so as to oversupply one chamber and under-supply the other.

In closed position, as shown in dotted lines in Fig. 2, shutter 2i contacts the opposite sides of chamber 25 at less than 90 from open position and is turnable to open position in one direction only. Openings 32 are preferably disposed on the side of shutter 2! opening outwardly so that in low speed positions openings 32 are on the induction, low pressure side of shutter 21.

Tube as, which supplies the intermediate and high speed fuel requirements, is known to deflect the air stream passing through chamber 25 in the direction of its free end. Various attempts have been made to overcome such deflection such as the use of vanes or extending the tube fully across the chamber with fuel openings on the induction side. All such attempts have met with only limited success. A principal difficulty invariably encountered is the tendency of the liquid fuel to collect on the wall of the chamber behind the tube and flow in a liquid state through the manifold passages into the nearest or lowermost cylinder or chamber.

In engines similar to engine I, with tube 29 disposed vertically, the air striking the tube tends to climb the tube to its free end, pick up the liquid fuel and throw the fuel against the upper side of chamber 25. Other fuel would flow down the back side of tube 29 and along the bottom of chamber 25. The fuel would then collect behind shaft 28 carrying shutter 21, and the fuel on the top side of chamber 25 would drop down and with the fuel on the bottom of the chamber 25, ultimately be carried into the crankcase chamber l2.

In engine I, according to the present invention, tube 28 is disposed horizontally and extends into chamber 25 so that the air is deflected by the tube to the side of the chamber and continues into passages 22 without direction into one or the other crank chamber.

Tube 29 should open toward the side of shutter 27' opening inwardly. Thus the deflection of air by tube 29 and shutter 21 corresponds and the fuel from tube 29 passes oppositely in chamber 25 of openings 32 Without interfering with the latter or with the shutter. The tube extends approximately to the center of chamber 25 and is spaced from shutter 21 so that the fuel cannot strike the shutter and the liquid particles collect.

The invention provides a delivery of fuel to passages 22 which is not directed by the tube or shutter of the carburetor. The air and fuel mixture is directed past shutter 21 into passages 22 without being allowed to collect behind the shutter.

Various embodiments of the invention may be carried out within the scope of the accompanying claims.

I claim:

1. In an internal-combustion engine having horizontally disposed cylinders, a carburetor having a fuel mixing passage extending in a plane parallel to said cylinders and opening at the outer end to receive air for combustion, a manifold having passages in communication with the inner end of the carburetor passage and extending at substantially right angles to the carburetor passage and in opposite directions therefrom to communicate with the corresponding cylinders of the engine, a shutter valve controlling said carburetor passage and having an axis generally parallel to said manifold passages, said. shutter valve being disposed to control the flow of air through the carburetor passage and rotatable to deflect the greater amount of air entering the passage to one side of the passage, and a jet tube extending into the passage of the carburetor in advance of the shutter valve and adapted to introduce liquid fuel into the carburetor passage for vaporization, said tube extending in a plane substantially from the axis of the shutter valve and having an open end to direct the fuel towards said one side of the passage so that the air deflected by the tube carries the liquid past the shutter valve with the greater part of the air passing the valve.

2. In an internal-combustion engine having horizontally disposed cylinders and adjacent upper and lower chambers for receiving a fuel mixture, a carburetor having a fuel mixing passage extending in a plane parallel to said cylinders and opening at the outer end to receive air for combustion, said engine having manifold passages in communication with the inner end of the fuel mixing passage of said carburetor and extending upwardly and downwardly therefrom to communicate with the corresponding upper and lower chambers of the engine, a shutter valve including a vane and a shaft disposed on an axis generally parallel to the manifold passages and supporting said vane within the passage of said carburetor for pivotal movement to control the passage, said vane being selectively movable between a closed position extending across the passage and an open position extending longitudinally and centrally of the passage, said shaft being rotatable within limits of approximately 90 to dispose said vane in either of said positions and any intermediate position wherein the air entering the passage of said carburetor is deflected by the vane toward one side of the passage and the greater amount of air passes on the corresponding side of the shaft and vane, and a jet tube extending horizontally into the passage of said carburetor between the outer open end thereof and said valve and adapted to introduce liquid fuel into the carburetor passage for vaporization, said tube being supported by the carburetor to extend into the carburetor passage in a plane substantially 90 from the axis of the shaft of the shutter valve and having an end opening to direct the liquid fuel toward said one side of the passage, the end opening of said tube being centrally located within the carburetor passage and disposed in advance of said valve respecting the movement of air through the passage whereby the air deflected by the tube toward said one side of the carburetor passage carries the liquid fuel from the free open end of the tube past said valve on said corresponding side of the shaft and vane.

3. The invention of claim 2 wherein the carburetor includes a smaller idling jet formed in the other side of the carburetor passage and controlled by said vane in a position substantially closing the passage.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,919,793 Linga July 25, 1933 2,118,761 Johnson May 24, 1938 2,185,506 Johnson Jan. 2, 1940 

